Following from Ontological Questions in Linguistics (2005) by Mulder and Rastall, The Power of Speech adopts a functional perspective to address a range of fundamental issues concerned with our understanding of speech acts and the role of theory, systems, and other constructs in our account.

In particular, the work explores the ideas that acts of speaking are "powers" in the philosophical sense and that "meaning" exists only in actual speech acts. Applying a rigorous ontological distinction between actually existing speech events in space, time and social circumstances, and theoretically determined constructs accounting for speech events and their aspects, the work distinguishes real communication from accounts of potentials for communication and potentials for meaning on the one hand, and from socially constructed beliefs about language on the other.

The work further explores Popper's views on the nature of language. It distinguishes language as communication from language as system or pattern and from language as information. For the latter the capacity to "arrest" speech and to consider it critically is central to understanding the role of linguistic mediation in rationality. However, by placing language in a biological and evolutionary context the work revisits the analogy/anomaly debate and emphasises the evidence for a more balanced and organic view of language along with its systematic features. The work draws attention to the need to explain the adaptation of linguistic constructs to ever-changing human needs and priorities and suggests some solutions.